Cinematography



July 27 1926.

5. J. COX

' GINBMATOGRAPHY Filed Oct. 20, 1923 2 Sheets-Sheet 1 Jul 27,192 1,593,796

S. J. COX

CINEIATOGRAPHY Filed Oct. 20, 192: ZShets-ShectZ t, [/WE/yTM s,J. Cox

Patented July 27,- 1926.

UNITED sTATEs PATENT OFFICE.

SANIUEL JAMES COX, OF LONDON, ENGLAND, ASSIGNOR TO CINECHROME INSTRU- MENTS, LIMITED, OF LONDON, ENGLAND. f

Application filed October 20, 1923, Serial No. 669,846, and in Great Britain OctoberJM, 1922.

The present invention ii elates to improvements in and relating to cinematography in which use is made'of a wide film, and being particularly applicable to that aspect of two colour cinematography in which a doublewiclth film is used, each pair of positive pictures across the width of the film being monochrome renderings by colour selection,

which when projected for superimposition on 1 the screen, simulate or give a suggestion or partial rendering of the colours of na, ture when the projection is through appropriately coloured light-filters, itwill be hereinafter described in that application.

Hitherto the projection the objection that a defect known as colourfringing is from time to time manifested by the appearance of bright flashing or changing marginal colours, this being frequently for lack of a steady'or straight run of the medial line of the film along a line which is medial to the two elements of the double gate of the projector. Or, in other words, and somewhat more loosely, the film should run truly and steadily to the double gate and to the pair of lenses.

The above mentioned colour fringing often arises pronouncedly when the positive film is printed from a composite negative film, or

made from various positive portions, the ne atives of which have been exposed in difierent cameras, and/or when the shrinkage has been unequal owing to peculiarities of the. film base or to varying conditions of time, temperature, or storage.

When such composite and irregular bands of negative film are printed, guidance from or by an ed e piece (or edge pieces) at the double gate ecomes unsatisfactory, and intolerable colour-fringing steps in "with re- 4 spect to some portions when the positive film is projected with its appropriate colour screening.

The present invention overcomes this dis- 5 advantage by promoting registration, and

reducing, eliminating, or avoiding the colour-fringing, or lack of registration.-

To this end, the resent invention broadly consists in means or giving positive guid-J ance to the filmalong the assumedmedlal line or imaginary. equator between the two series of colour selection or other pictures in place of the false or imperfect guidance from tion for" me ial guidance thereunder which has been found to work well in relation to film suited. to run on ta-long sprocket which is also adapted tote-kc theordinary standard or single width. film is shown I full size in a side guide to the gating area, or of depend ence on the driving organs for mediallzing.

the more readily understood reference is ad to the accompanying drawings, which illustrate, by we of example only, a construcintermittent-moving printing machines.

In the drawings j Fig. 1 shows a piece of double width film having a. medial rank of perforations for the purpose described between the usual two driving rows of perforations at the edges. as been open to' Figs. 2 and-3 are front and side views respectively of the feed and other mechanism mount of a two colour printer incorporating a guiding or registering device according to the present invention.

To carry this medial guidance into practical efi'ect, there is made in the double-width film a midway or thereabouts between the tapering organs which,-at a flaccid part'oii 80 the film, advance through the perforations in sequence and finally fit well into "or' contact to a fit-with the ends or sides of the perforations d, to give to the film the correct medial set or position at the gate aperture. By ends .or sides are meant those bounding edges of the. perforationsin the direction of the frun of the film as dis tinguished from the tops or bottoms which are at'right angles to the direction off-the run of thefilm. W These medial or extra perforations-d may be denominated the equating ,perforations nal"per forations 6, 0 which servejfor driving pr traction purposes, andfalmfffrom the medial row of perforations'in wide film; ,used fortractionpur s..."

: A working exampeflofq double width Fig. 1, and illustrates a scale and shape for the equating perforations which hasgiven good results, that is to say, the length of an equating perforationjisj ag great as the In order'that the present invention ma 'be two usual driving-rows of perforations b, c at the edges, a medial rank or row ofp'er space between the pictures conveniently al lows, which in general for ordinary purposes will at least equal in width a standard pressure guide margin, and the height, or dimension in the direction of the run of the film is less than the length;'very ap.' proximately half. Further the ends of the equating perforations are not straight but arched.

Vhile the film is being led into the gate aperture, it is positively guided by the tapering organs into the correct medial set or position as stated above. A fit or grip of a pointed organ (or steady pin) on the long sides of the perforations, or top and bottom is not desirable.

A working example of steady pin guidance which serves well for the purposes of the present invention is depicted in Figs. 2 and 3, being as preferred that it should be a tapering rectangular tooth of an idling sprocket e mounted over and near the double printing gate f and gearing into the row of equating perforations (Z, the sprocket e being idle as to rotation but firmly mounted as shewn in Fig. 2 against endwise or sidewise motion and firm against fiexions like the fiexions of a circular saw.

The double-widthnegative and positive films g, h, travel from their appertaining spools under a guide roller 2' between the sprocket g and pressure or bolster rollers g g thence, after looping, between the idling sprocket e and pressure or bolster roller 6' and through the printing gate f, being clawed down intermittently by suitable claw mechanism not shewn. From the printing gate f the films travel over a bottom sprocket not shewn and are wound on spools, or, alternatively the printed positive may be passed directly into the developing apparatus.

All parts of the printer not shown are readily understood by those versed in the art.

The course of the films is indicated by the morse line 7', dash line 70, and full line Z.

When the idling sprocket e is used, it is obvious that a plurality of'teeth must gear into the equating perforations 03 so that various similar steady pins or a plurality thereof, for example, two, depending on the wrap of the film, come into the final or culminating position in sequence. In order to facilitate the entry and leaving of the teeth which actas steady pins there should not be too much wrap of the film on the idling sprocket. A four teeth wrap as shewn in Fig. 3 gives good results, two teeth being in the final or culminating position at the same time.-

' By the term steady pin when used in reference to the pointed organ or a. tooth of the idling sprocket is to be understood a pin that is steady in relation to a transverse movementofthe stripof film.

While the medial guidance of the double width film may be effected in the camera, in the printer or in the projector or in any similar or like device or apparatus having a multiple function, as in all cases the pres ent invention conduees to steadiness and good register, the present invention is of special importance in relation to the printer as already explained.

In the printer the device according to the present invention not only brings each pair of negative pictures into register with the positive film by common reference to a medial perforation but it more or less perfectly equates and averages differences in width arising from the causes previously men tioned.

Thus what would otherwise be intolerable colour fringing or want of register is brought to somethingwhich is relatively unimportant.

It is to be noted that all film stock for use in relation to the present invention is similarly perforated, whether for positive or negative.

Although we have spoken in the chosen example of the generally preferred intermittent moving apparatus, the herein described system of retaining a broad or two picture film of the kind described approximately medial and true to path may be incorporated in continuously moving apparatus and such an application is to be regarded as forming part of the present invention and included in the claims hereof.

The invention is also available in relation to other broad films than colour films of the kind described, for example, broad cinematographic films for the production of stereoscopic effects, where it is desirable to promote steady running and true registration.

It is not essential for the purposes of the present invention to provide the films with the usual driving rows of perforations as these may be replaced by rows of clearing holes, or in some cases dispensed with alto gether, and use made of the medial rank or ,row of equating perforations for driving or traction purposes as well asfor medially setting or positioning purposes, appropriate feed mechanism being of course provided.

One advantage of a film medially perforated midway between the edges is that it can be threaded up in reverse-aspect if a back projection is desired to be made.

What I claim is 1. In and in connection with broad cinematographic films of the kind described, the combination for' promoting steady running and true registration of a broad film, or two such films, embodying a. series of tapering organs or steady pins and a medial rank of" equatingperforations so formed, arranged and operating that while the filni'or films are being led'to thegate aperture the film or films are positively guided by the steady pins'into the correct medial set or position substantially as and for the pur poses described;

2 Means for; retaining a broad film or two such films of the kind described approximately medial and true to path in a "cinematographic apparatus, comprising a rank of equating perforations in the film 1 and an idling sprocket in said apparatus gearing with said perforations, the teeth of said idling sprocket being of a width so as to engage with the shorter dimension sides of the appropriate perforations while the film, or two such films is or are being led to the gate aperture, for the purposes described.

In testimony whereof, I atfix my signature.

SAMUEL JAMES COX. 

